- Treated startup scoped model selection as a prompt-cache shape override before inheriting fork cache keys.
- Covered the --models fork path so a scoped startup model cannot reuse the parent prompt_cache_key.
Fixes#5035
- Persisted an inherited provider prompt-cache key on full session forks while keeping the child OMP session id independent.
- Added --prompt-cache-key and SDK startup inheritance so explicit cache affinity is separate from provider session routing.
- Cleared automatic inherited keys when model, thinking, system prompt, or tool schema inputs change.
Fixes#5035